diff --git a/tests/common_test_class.py b/tests/common_test_class.py
index 034cc2f5..8174ccc1 100644
--- a/tests/common_test_class.py
+++ b/tests/common_test_class.py
@@ -156,7 +156,7 @@ class AbstractPillarTest(TestMinimal):
         """
 
         if isinstance(roles, str):
-            roles = set(roles)
+            roles = {roles}
 
         # Create a service account if needed.
         if srv_token is None: